The majority of the bacteria, viruses and proteins that come in contact with the body are present through the mucosal immune system. Studies done in rats, mice and rabbits in which cells from Peyers Patches, mesenteric lymph nodes or thoracic duct lymph are transferred to a secondary host (1-4) indicate that lymphocytes sensitized to antigen at the mucosal surfaces must migrate through the local lymphatics and the peripheral circulation prior to terminal differentiation at the mucosal surfaces. We will take advantage of this migrational pattern to study the kinetics and cellular requirements for an immune response to antigen delivered to the mucosal surfaces. Healthy adults will be given primary and secondary oral immunizations with the soluble protein antigen, keyhole limpet hemocyanin (KLH), sequential blood samples will be drawn and the ability of cultured lymphocytes to spontaneously secrete antibody or be stimulated to produce antigen specific antibody will be analyzed. Supernatants will be harvested after 10 days of cell culture and the amount of anti-KLH antibody of IgM, IgG and IgA isotype will be quantitated by an ELISA assay. The peak and duration of a primary response will be compared to that of a secondary. Antigen sensitization will be examined by studying the 3H thymidine uptake of cells obtained after immunization. The T cell requirements for the antibody response will be evaluated by separating T cells and B cells. B cells will be cultured alone, with media containing T cell replacing factors, with non-immune T cells obtained prior to immunization, or with immune T cells. The role T cell suppressors will be examined by comparing the effects of irradiated and non-irradiated T cells and T cells that express the T helper phenotype (OKT4) on antigen specific antibody production. To assess the effects of mitogens with differing cell targets on KLH specific antibody production, lymphocytes will be cultured with the mitogens ConA, LPS and pokeweed mitogen. These cultures will be done both with and without the antigen KLH. To characterize the B cells that differentiate into antibody producing cells, B cells will be separated on the basis of expression of surface IgM, cell size and density or intensity of Ia expression. The results of these studies should provide valuable information about normal regulation of the mucosal immune system. This information should be useful in the development of optimal strategies for mucosal immunization. It should also provide new insights into our understanding of the aberrent regulatory mechanisms that result in the development of allergy and inflammatory bowel disease.